Service providers sell and distribute desk phones (e.g., Voice over Long Term Evolution (VoLTE) for Business, Session Initiation Protocol (SIP) multimedia desk phones, etc.) to customers (e.g., business customers). The service providers may provision and put phones into service. SIP phones may be deployed to a wide variety of customer locations with a wide variety of network configurations (e.g., including routers, network address translators (NATs), firewalls, session border controllers, application layer gateways, etc.).